A multidisciplinary approach combining neurophysiology, neuroanatomy and psychophysics is proposed to study the neuronal processing of tactile information from controlled natural cutaneous stimuli, and to examine the neurophysiological basis of a simple cognitive process. The aim of the proposed research is to examine the neurophysiological activity produced in the somatosensory regions of the primate cerebral cortex by objects of defined spatial geometries and textured surfaces of known spatial frequencies applied in a controlled fashion to the glabrous skin of the hand. Using extracellular single unit recording techniques in monkeys trained to perform sensory discrimination tasks, I will compare the responses of simple cortical neurons involved in the perception of spatial details of cutaneous stimuli with activity in higher-order feature-detecting neurons postulated to abstract specialized types of information from these stimuli. Feature-detecting neurons will provide a model system for examining the neurophysiological basis of one type of cognitive process: the formulation of abstract concepts from detailed sensory perceptions. Neuroanatomical techniques involving retrograde and anterograde transport of horseradish peroxidase will be used to determine microcircuitry of cortical regions containing high densities of feature-detecting neurons. These investigations may yield answers to the following questions: What are the neural mechanisms of edge detection on the skin? What is the mechanism underlying direction-sensitivity of cortical neurons? What is the neural mechanism underlying stereognosis? What cortical mechanisms are involved in texture discrimination? Do feature-detecting neurons represent hierarchical or parallel processing modes of information processing? Answers to these questions will be useful not only for understanding somatosensory functions of the cerebral cortex, but may provide insight into some neurophysiological mechanisms underlying a simple cognitive process.